Metabolomics approach discriminates toxicity index of pyrazinamide and its metabolic products, pyrazinoic acid and 5-hydroxy pyrazinoic acid

Pyrazinamide (PYZ)-an essential component of primary drug regimen used for the treatment and management of multidrug resistant or latent tuberculosis-is well known for its hepatoxicity. However, the mechanism of PYZ-induced hepatotoxicity is still unknown to researchers. Studies have shown that the drug is metabolized in the liver to pyrazinoic acid (PA) and 5-hydroxy pyrazinoic acid (5-OHPA) which individually may cause different degrees of hepatotoxicity. To evaluate this hypothesis, PYZ, PA, and 5-OHPA were administered to albino Wistar rats orally (respectively, at 250, 125, and 125 mg kg^-1 for 28 days). Compared to normal rats, PYZ and its metabolic products decreased the weights of dosed rats and induced liver injury and a status of oxidative stress as assessed by combined histopathological and biochemical analysis. Compared to normal controls, the biochemical and morphological changes were more aberrant in PA- and 5-OHPA-dosed rats with respect to those dosed with PYZ. Finally, the serum metabolic profiles of rats dosed with PYZ, PA, and 5-OHPA were measured and compared with those of normal control rats. With respect to normal control rats, the rats dosed with PYZ and 5-OHPA showed most aberrant metabolic perturbations in their sera as compared to those dosed with PA. Altogether, the study suggests that PYZ-induced hepatotoxicity might be associated with its metabolized products, where 5-OHPA contributes to a higher degree in its overall toxicity than PA.

Role of Antibiotic Cement Coated Nailing in Infected Nonunion of Tibia

Introduction

Infected nonunion of long bones is a chronic and debilitating disorder. It is more difficult to deal with when the implant used for internal fixation itself becomes a potential media for infection because of bacterial adhesion and biofilm formation. Traditionally, it is managed by two-stage procedure for controlling the infection first and then treating the nonunion. This study has been undertaken to explore antibiotic cement coated nailing as single stage treatment modality for treating infection and achieving stability at the same time.

Materials and Methods

Twenty patients (above 18 years of age) with infected nonunion of tibia with bone gap less than 2 cm were managed using antibiotic cement coated K-nail. Antibiotic cement nail was prepared using endotracheal tube method. Antibiotics used were a combination of vancomycin and teicoplanin.

Results

Infection was controlled in 95% of the patients. Bony union was achieved in 12 of 20 (60%) patients with antibiotic cement nailing as the only procedure with average time of union of 32 weeks. Remaining 8 patients required additional procedures like bone grafting or exchange nailing and these were done in six patients, with union of fracture. Two patients refused to undergo further procedures. Complications encountered were difficult nail removal in three cases, broken nail in two cases, and bent nail in one case. Recurrence of infection was observed in two patients. Average period of follow-up was 13 months.

Conclusion

Antibiotic cement impregnated nailing is a simple, economical and effective single stage procedure for the management of infected nonunion of tibia. It is advantageous over external fixators, as it eliminates the complications of external fixators and has good patient compliance. The method utilizes existing easily available instrumentation and materials and is technically less demanding, and therefore can be performed at any general orthopaedic center.

Multivalency in Rab effector interactions

Rab proteins regulate vesicular transport in eukaryotic cells and establish connections to various cellular structures and processes by interacting with so-called effector molecules. Several of these effectors are known to not only bind a single Rab protein, but to be able to bind multiple different Rabs simultaneously. In this review we will give a short overview of effectors in general and (putative) functions of the aforementioned multivalent Rab:effector interactions.

The ‘three-legged stool’

Many hospitals do not have a structured process of consent, the attainment of which can often be rather ‘last-minute’ and somewhat chaotic. This is a surprising state of affairs as spinal surgery is a high-risk surgical specialty with potential for expensive litigation claims. More recently, the Montgomery ruling by the United Kingdom Supreme Court has placed the subject of informed consent into the spotlight.

There is a paucity of practical guidance on how a consent process can be achieved in a busy clinical setting. The British Association of Spinal Surgeons (BASS) has convened a working party to address this need. To our knowledge this is the first example of a national professional body, representing a single surgical specialty, taking such a fundamental initiative.

In a hard-pressed clinical environment, the ability to achieve admission reliably on the day of surgery, in patients at ease with their situation and with little likelihood of late cancellation, will be of great benefit. It will reduce litigation and improve the patient experience.

Cite this article: Bone Joint J 2016;98-B:1427–30.

An efficient algorithm for protein structure comparison using elastic shape analysis

BACKGROUND

Protein structure comparison play important role in in silico functional prediction of a new protein. It is also used for understanding the evolutionary relationships among proteins. A variety of methods have been proposed in literature for comparing protein structures but they have their own limitations in terms of accuracy and complexity with respect to computational time and space. There is a need to improve the computational complexity in comparison/alignment of proteins through incorporation of important biological and structural properties in the existing techniques.

RESULTS

An efficient algorithm has been developed for comparing protein structures using elastic shape analysis in which the sequence of 3D coordinates atoms of protein structures supplemented by additional auxiliary information from side-chain properties are incorporated. The protein structure is represented by a special function called square-root velocity function. Furthermore, singular value decomposition and dynamic programming have been employed for optimal rotation and optimal matching of the proteins, respectively. Also, geodesic distance has been calculated and used as the dissimilarity score between two protein structures. The performance of the developed algorithm is tested and found to be more efficient, i.e., running time reduced by 80-90 % without compromising accuracy of comparison when compared with the existing methods. Source codes for different functions have been developed in R. Also, user friendly web-based application called ProtSComp has been developed using above algorithm for comparing protein 3D structures and is accessible free.

CONCLUSIONS

The methodology and algorithm developed in this study is taking considerably less computational time without loss of accuracy (Table 2). The proposed algorithm is considering different criteria of representing protein structures using 3D coordinates of atoms and inclusion of residue wise molecular properties as auxiliary information.

bMERB domains are bivalent Rab8 family effectors evolved by gene duplication

In their active GTP-bound form, Rab proteins interact with proteins termed effector molecules. In this study, we have thoroughly characterized a Rab effector domain that is present in proteins of the Mical and EHBP families, both known to act in endosomal trafficking. Within our study, we show that these effectors display a preference for Rab8 family proteins (Rab8, 10, 13 and 15) and that some of the effector domains can bind two Rab proteins via separate binding sites. Structural analysis allowed us to explain the specificity towards Rab8 family members and the presence of two similar Rab binding sites that must have evolved via gene duplication. This study is the first to thoroughly characterize a Rab effector protein that contains two separate Rab binding sites within a single domain, allowing Micals and EHBPs to bind two Rabs simultaneously, thus suggesting previously unknown functions of these effector molecules in endosomal trafficking.

DOI:http://dx.doi.org/10.7554/eLife.18675.001

P14: DOXYCYCLINE: A RARE CAUSE OF DRUG INDUCED PANCREATITIS

Purpose of Study

Drug-induced pancreatitis (DIP) is a rare clinicopathologic entity. We report a 58-year-old female who developed DIP secondary to administration of doxycycline.

Methods Used

A 48 year old female with a history of hypertension presented to the hospital with complains of nausea/vomiting, right upper-quadrant gnawing abdominal pain, 8/10 in intensity with radiation to the back. She denied exacerbating factors, use of alcohol, tobacco and drug. Patient also denied diarrhea, constipation and changes in skin or stool color. On examination patient was hypertensive (155/95) with a heart rate of 102. She had epigastric/right upper quadrant tenderness on superficial palpation, hypoactive bowel sounds without any palpable organs, rebound tenderness or rigidity. Serum lipase was elevated at 2508 IU/L, negative pregnancy and insignificant urinalysis findings. Liver function tests, lipid panel, chemistry panel and hematologic panel were within normal limits. Radiologic investigations with abdominal ultrasound depicted mild proximal dilatation of the common bile duct with smooth tapering of the duct distally indicating status post-cholecystectomy. Contrast enhanced computed tomography scan revealed mild enlargement of the body of the pancreas with adjacent peripancreatic fatty infiltration consistent with acute pancreatitis. Upon further questioning patient explains recent diagnosis (7 days) of tibial orthopedic hardware infection as she was prescribed doxycycline 200 mg twice a day in anticipation of irrigation of infected site. After confirmation, and discontinuation of doxycycline, our patient recovered and has been disease-free for over a month.

Summary of Results

Drug-induced pancreatitis is uncommon etiology of acute pancreatitis, which is responsible for 0.1%–2% of all the acute pancreatitis cases. Among adverse drug reactions, pancreatitis is often-ignored because of the difficulty in implicating a drug as its cause.

Conclusions

In our vastly evolving pharmacotherapy world, DIP should be included in the differential of idiopathic pancreatitis, especially after other common causes have been ruled out.

A pull-down procedure for the identification of unknown GEFs for small GTPases

Members of the family of small GTPases regulate a variety of important cellular functions. In order to accomplish this, tight temporal and spatial regulation is absolutely necessary. The two most important factors for this regulation are GTPase activating proteins (GAPs) and guanine nucleotide exchange factors (GEFs), the latter being responsible for the activation of the GTPase downstream pathways at the correct location and time. Although a large number of exchange factors have been identified, it is likely that a similarly large number remains unidentified. We have therefore developed a procedure to specifically enrich GEF proteins from biological samples making use of the high affinity binding of GEFs to nucleotide-free GTPases. In order to verify the results of these pull-down experiments, we have additionally developed two simple validation procedures: An in vitro transcription/translation system coupled with a GEF activity assay and a yeast two-hybrid screen for detection of GEFs. Although the procedures were established and tested using the Rab protein Sec4, the similar basic principle of action of all nucleotide exchange factors will allow the method to be used for identification of unknown GEFs of small GTPases in general.

Risk Factors and Outcome of Neonates Born through Meconium Stained Amniotic Fluid in a Tertiary Hospital of Nepal

Introduction: The incidence of meconium aspiration syndrome is still high in the developing world contributing significantly to the neonatal mortality. The study was aimed to know the risk factors contributing to meconium aspiration syndrome and neonatal outcome in a tertiary government hospital of the country.Materials and Methods: It was a hospital based cross sectional study done over a period of three months. All live newborns born through meconium stained liquor were enrolled and all the details regarding mother, neonate were recorded. Odd’s ratio and bivariate analysis was done to assess the risk factors for meconium aspiration syndrome.Result: Out of all the deliveries 14.6% were meconium stained amniotic fluid and meconium aspiration syndrome developed in 6.6% of the neonates. Low Apgar score and premature rupture of membranes was significantly associated with the risk of occurrence of meconium aspiration syndrome. Neonates who developed meconium aspiration syndrome had mortality of 11.3%.Conclusion: Perinatal asphyxia and premature rupture of membranes were significantly associated with the development of meconium aspiration syndrome and neonates who developed meconium aspiration syndrome had high mortality.J Nepal Paediatr Soc 2015;35(1):44-48